JP-A-10-152477 describes a process for preparing a 4-arylaminoquinazoline compound from a quinazolin-4-one, which comprises the steps of chlorinating 4-iodoquinazolin-4-one using an excessive amount of oxalyl chloride to produce 6-iodo-4-chloroquinazoline (intermediate compound), concentrating the reaction product under reducing pressure to isolate the resulting product; reacting the 6-iodo-4-chloroquinazoline with 5-aminoindole to give 6-iodo-4 (5-indolylamino)quinazoline. Unfortunately, the yield is not high. Further, it should be noted that the intermediate compound, i.e., 4-chloroquinazoline compound, shows no satisfactory stability in the presence of water and no satisfactory resistance to heat. Accordingly, the compound should be handled carefully.
WO 96/09294 describes a process for preparing 6-halogeno-4-chloroquinazoline from 6-halogenoquinazolin-4-one which comprises reacting the 6-halogenoquinazolin-4-one with an excessive amount of phosphorus oxychloride. This process, however, has problems in that a large amount of smelly phosphorus oxychloride should be used, yield of the reaction product (i.e., 6-halogeno-4-chloroquinazoline) is low, and a large amount of an organic solvent is necessarily employed for recovering the reaction product from an excessive amount of phosphorus oxychloride. Thus, complicated post-treating procedures are required.